🚀 go-pugleaf

"Bob Keeter" <rkeeter@earthlink.net> wrote in message news:<O13fc.6756$zj3.3903@newsread3.news.atl.earthlink.net>...
> "Daryl Krupa" <icycalmca@yahoo.com> wrote in message
> news:c70365ef.0404122219.86130be@posting.google.com...
> Snip. . .
>
> >   I like the theory that the sites most likely to have had evidence
> > of human habitation at earlier dates, further north, have been
> > plowed up by glaciers, covered with loess, scoured out by glacial
> > meltwater, buried under alluvium, mined for marl or bat guano, or
> > maybe never had anything that could easily be recognised as having
> > been the result of early human activity before it was irrevocably
> > disturbed by modern humans and their advanced technology.
> >
> > Daryl Krupa
>
> Well, thats possible.  But lets think about it for a moment.
> If this migration occurred lets say 60kya,
> there would be several glacial advances between then and now
> and a lot of "earthmoving" could have occured.
> If I go back 30kya, there is progressively fewer "advances", and
> more of a pseudo "static situation" and retreat of the glaciers,
> right?

  The timing of Early Wisconsinan advance and recession
is not well-dated, and its extent varied:
in some places (western side of LIS)
it was less extensive than the Late Wisconsinan advance,
and in other places
it was more extensive than the Late Wisconsinan advance.
  The Middle Wisconsinan interstadial
("period of reduced ice extent within a generally glacial time")
lasted from _roughly_ 50-25 ka BP.
  So, at 60 ka BP, conditions would be cold and glacial, but
there was probably an ice-free strip between the LIS and the Rockies.
  After that, the Laurentide Ice Sheet (LIS)
retreated to the Canadian Shield, and
a wide ice-free strip existed east of the Rockies,
including at 30 ka BP.
  After that, the LIS expanded,
probably reaching farther west than ever before, and
coalesced with overflow from the Cordilleran Ice Sheet (CIS),
which was spilling over mountain passes through the Rockies
from British Columbia.

> How does that get you "plowed under"?

  I was positing migration into North America on foot
during the Middle Wisconsinan interstadial.
  After that initial migration,
ice advanced over the migration path,
and also over other potentially inhabited areas
south and southeast of the LIS.
  Glacier advance usually involves removal of the pre-existing
surface materials. That is what I meant by "plowed up".
  I don't know how that gets me '"plowed under"'.

> As for the possible interference by modern humans and such,. . .
> would not that same agent have destroyed all evidence of Folsom
> and Clovis as well?

  No, not necessarily; Clovis and Folsom people may have found that
areas that are not well-suited to agriculture today
(or other means of disturbance)
were well-suited to them; e.g., in New Mexico.
  Also, Clovis and Folsom material would be nearer
the surface of the soil, and so easier to notice.
  Older material would have had more opportunity to be
damaged beyond recognition, buried beyond easy retrieval, or
disturbed by later humans (with "modern" humans I suppose I would
include agricultural societies before Columbus crashed the party).

Daryl Krupa